[fsp] Add support for truncating files.

chrome/test/data/extensions/api_test/file_system_provider/truncate/test.js

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+'use strict';
+
+/**
+ * @type {string}
+ * @const
+ */
+var TESTING_TIRAMISU_FILE_NAME = 'tiramisu.txt';
+
+/**
+ * Requests truncating a file to the specified length.
+ *
+ * @param {TruncateRequestedOptions} options Options.
+ * @param {function()} onSuccess Success callback.
+ * @param {function(string)} onError Error callback.
+ */
+function onTruncateRequested(options, onSuccess, onError) {
+  if (options.fileSystemId != test_util.FILE_SYSTEM_ID) {
+    onError('SECURITY');  // enum ProviderError.
+    return;
+  }
+
+  if (!(options.filePath in test_util.defaultMetadata)) {
+    onError('INVALID_OPERATION');  // enum ProviderError.
+    return;
+  }
+
+  var metadata = test_util.defaultMetadata[options.filePath];
+
+  // Truncating beyond the end of the file.
+  if (options.length > metadata.size) {
+    onError('INVALID_OPERATION');
+    return;
+  }
+
+  metadata.size = options.length;
+  onSuccess();
+}
+
+/**
+ * Sets up the tests. Called once per all test cases. In case of a failure,
+ * the callback is not called.
+ *
+ * @param {function()} callback Success callback.
+ */
+function setUp(callback) {
+  chrome.fileSystemProvider.onGetMetadataRequested.addListener(
+      test_util.onGetMetadataRequestedDefault);
+  chrome.fileSystemProvider.onOpenFileRequested.addListener(
+      test_util.onOpenFileRequested);
+  chrome.fileSystemProvider.onCloseFileRequested.addListener(
+      test_util.onCloseFileRequested);
+  chrome.fileSystemProvider.onCreateFileRequested.addListener(
+      test_util.onCreateFileRequested);
+
+  test_util.defaultMetadata['/' + TESTING_TIRAMISU_FILE_NAME] = {
+    isDirectory: false,
+    name: TESTING_TIRAMISU_FILE_NAME,
+    size: 128,
+    modificationTime: new Date(2014, 1, 24, 6, 35, 11)
+  };
+
+  chrome.fileSystemProvider.onTruncateRequested.addListener(
+      onTruncateRequested);
+
+  test_util.mountFileSystem(callback);
+}
+
+/**
+ * Runs all of the test cases, one by one.
+ */
+function runTests() {
+  chrome.test.runTests([
+    // Truncate a file. It should succeed.
+    function truncateFileSuccess() {
+      var onTestSuccess = chrome.test.callbackPass();
+      test_util.fileSystem.root.getFile(
+          TESTING_TIRAMISU_FILE_NAME,
+          {create: false, exclusive: true},
+          function(fileEntry) {
+            fileEntry.createWriter(function(fileWriter) {
+              fileWriter.onwriteend = function(e) {
+                // Note that onwriteend() is called even if an error happened.
+                if (fileWriter.error)
+                  return;
+                chrome.test.assertEq(
+                    64,
+                    test_util.defaultMetadata[
+                        '/' + TESTING_TIRAMISU_FILE_NAME].size);
+                onTestSuccess();
+              };
+              fileWriter.onerror = function(e) {
+                chrome.test.fail(fileWriter.error.name);
+              };
+              fileWriter.truncate(64);
+            },
+            function(error) {
+              chrome.test.fail(error.name);
+            });
+          },
+          function(error) {
+            chrome.test.fail(error.name);
+          });
+    },
+
+    // Truncate a file to a length larger than size. This should result in an
+    // error.
+    function truncateBeyondFileError() {
+      var onTestSuccess = chrome.test.callbackPass();
+      test_util.fileSystem.root.getFile(
+          TESTING_TIRAMISU_FILE_NAME,
+          {create: false, exclusive: false},
+          function(fileEntry) {
+            fileEntry.createWriter(function(fileWriter) {
+              fileWriter.onwriteend = function(e) {
+                if (fileWriter.error)
+                  return;
+                chrome.test.fail(
+                    'Unexpectedly succeeded to truncate beyond a fiile.');
+              };
+              fileWriter.onerror = function(e) {
+                chrome.test.assertEq(
+                    'InvalidModificationError', fileWriter.error.name);
+                onTestSuccess();
+              };
+              fileWriter.truncate(test_util.defaultMetadata[
+                  '/' + TESTING_TIRAMISU_FILE_NAME].size * 2);
+            },
+            function(error) {
+              chrome.test.fail();
+            });
+          },
+          function(error) {
+            chrome.test.fail(error.name);
+          });
+    }
+  ]);
+}
+
+// Setup and run all of the test cases.
+setUp(runTests);